This invention relates to a power supply arrangement for providing auxiliary power to the electrical system of a building, such as from a standby generator or the like.
Portable generators are used in certain situations to supply electrical power to residential and commercial load circuits during a utility power outage. A system for interconnecting the generator with the load center of a building typically includes a power inlet box having a receptacle for receiving a plug extending from the generator.
The power inlet box is typically mounted to the exterior of a building, and is adapted for connection to a transfer switching mechanism which establishes an electrical path between the generator and the load center. The transfer switching mechanism typically includes a series of switches and circuit breakers, which are operable to supply power to certain selected circuits of the load center. The circuits of the transfer switching mechanism are wired to selected circuits of the load center, through wiring housed within a conduit extending between the transfer switching mechanism and the load center.
A typical transfer switching mechanism includes a housing provided with a power input receptacle. The remote power inlet box is wired to a power cord connected to a junction box, and the power cord is engageable with the power input receptacle of the transfer switching mechanism so as to provide power to the transfer switching mechanism from the generator. An alternative arrangement is illustrated in Flegel U.S. Pat. No. 5,895,981 issued Apr. 20, 1999, the disclosure of which is hereby incorporated by reference. In the '981 patent, the transfer switching mechanism includes a terminal compartment within which a set of terminals is located. The terminals are wired to the switches of the transfer switching mechanism. A set of power input wires extends from the power inlet box, and into the terminal compartment of the transfer switching mechanism. The ends of the power input wires are connected to the terminals, to establish a direct, non-plug type connection between the power inlet box and the transfer switching mechanism.
U.S. Pat. No. 6,414,240 issued to Flegel on Jul. 2, 2002 describes a power transfer switching mechanism that includes a cabinet defining an internal cavity within which a series of switches are mounted. One or more lead wires are connected to the switches, and define ends which extend into a compartment. The compartment is accessible through an opening associated with the cabinet, and a cover is selectively positionable over the opening to provide or prevent access to the compartment. With the cover removed, the lead wires can be connected to power input wires in a conventional manner, e.g., wire-to-wire connectors, and the wires and the connectors may then be placed within the compartment and concealed by attaching the cover to the cabinet. The internal cavity is segmented into upper and lower compartments by a transverse wall that is integrally formed with a front panel of the cabinet. More particularly, the front panel is bent rearwardly at its lower end to form the transverse wall.
The present invention provides a power transfer switching mechanism that improves upon the advancements to the art provided by the '240 patent to Flegel. More particularly, in accordance with one embodiment of the present invention, a power transfer switching mechanism includes a cabinet defining an internal cavity that is segmented into first and second compartments by an intermediate and removable transverse wall member. The cabinet is generally defined by a back wall and a pair of sidewalls extending transversely outwardly from the back wall, and which may be integrally formed with the back wall. A mating engagement arrangement is interposed between the base and the intermediate wall member. The mating engagement arrangement may be in the form of a channel formed along the inner surface of the back wall and along facing inner surfaces of the sidewalls. The intermediate wall member may be configured for engagement within the channel, and functions to partition the cabinet into first and second sections. In one embodiment, a first (or upper) panel engages portions of the sidewalls and the intermediate wall member, and is configured to fit over the first section to define the first or upper compartment. In a similar fashion, a second (or lower) panel engages portions of the sidewalls and the intermediate wall member, and is configured to fit over the second or lower section to define the second or lower compartment.
A series of switches is mounted to the first panel, and in a preferred method of manufacturing the power transfer switching mechanism, the switches are mounted to the first panel before the first panel is secured to the back wall. Lead wires are interconnected with the switches. The lead wires define ends which extend into and are located within the second compartment. The ends of the lead wires are adapted for engagement with a power input interconnected with the auxiliary power source, such that the lead wires establish an electrical path between the power input and the switches.
The power input may be in the form of a series of power input wires which extend from a remote power inlet box, which includes a power input receptacle for receiving a plug-type connector extending from the auxiliary power source, such as a portable generator. In this embodiment, the power input wires are connected to the ends of the lead wires, such as by twist-on connectors. Once the appropriate connections have been made, the wire ends and connectors are placed within the second compartment of the power transfer device housing. The second panel is secured in place over the second compartment, so as to enclose the second compartment within which the wire ends and the connectors are located.
A strain relief arrangement may be engaged with the wire leads at a location spaced from the switches. The strain relief arrangement includes a clamp that is fastened to the back wall of the second compartment by a pair of threaded fasteners. As the fasteners are tightened using a suitable driver, the clamp is driven toward the back wall. In doing so, the wire leads extending into the second compartment are pushed toward, and eventually held tight against, the back wall of the second compartment. This arrangement prevents the inadvertent or unintentional disconnection of the wires from the switches as the wires are being connected to a power input.
Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings.